[gmx-users] hdb file

Moeed lecielll at googlemail.com
Thu Jul 1 23:12:52 CEST 2010


Dear Justin,

Thanks so much for your help. The structure looks almost fine now.

1-I am getting bond distance of 1.52 or 1.53 and angles of 112.2 / 112.0
with -d 0.0584/ 0.0581. Actually when I open up the same structure file in
VMD at different times I see even a little difference in bond distance
between atoms *on* the 4C unit chain (1.54 , 1.53 A). Thats why I though
maybe 1 or 2 degrees difference from equilibrium value of 110 for connecting
atoms does not influence results..But still I wanted to make sure if I need
to do energy minimization to get exact value of 110 for angles between
repeating units and if this is going to affect simulation results?

2- I am trying to obtain top and gro file including H atoms with hdb abd rtp
files. I am not getting any error messages and it seems everything is going
well but the gro file after adding H s has a very weird structure. I doubt I
have wriiten hdb file correctly. Could you please take a look at it?

editconf -f 4C.gro -o 4Cd.gro -princ -d 0.0584 -bt cubic

4Cd.gro

Great Red Owns Many ACres of Sand
    4
    1Eth     C1    1   0.445   0.268   0.252
    1Eth     C2    2   0.308   0.199   0.252
    1Eth     C3    3   0.196   0.304   0.252
    1Eth     C4    4   0.058   0.238   0.252
   0.50416   0.50416   0.50416

editconf -f 4Cd.gro -o 4Cdindex.gro -n index.ndx -princ

Great Red Owns Many ACres of Sand
    4
    1Eth     C1    1   0.446   0.286   0.252
    1Eth     C2    2   0.321   0.198   0.252
    1Eth     C3    3   0.195   0.286   0.252
    1Eth     C4    4   0.068   0.201   0.252
   0.50416   0.50416   0.50416

genconf -f 4Cdindex.gro -o 4Cdindex-rep.gro -nbox 5 1 1

 4Cdindex-rep: with residues renamed

 20
    1EthB    C1    1   0.446   0.286   0.252  0.0000  0.0000  0.0000
    1EthB    C2    2   0.321   0.198   0.252  0.0000  0.0000  0.0000
    1EthB    C3    3   0.195   0.286   0.252  0.0000  0.0000  0.0000
    1EthB    C4    4   0.068   0.201   0.252  0.0000  0.0000  0.0000
    2Eth     C1    5   0.950   0.286   0.252  0.0000  0.0000  0.0000
    2Eth     C2    6   0.825   0.198   0.252  0.0000  0.0000  0.0000
    2Eth     C3    7   0.699   0.286   0.252  0.0000  0.0000  0.0000
    2Eth     C4    8   0.572   0.201   0.252  0.0000  0.0000  0.0000
    3Eth     C1    9   1.454   0.286   0.252  0.0000  0.0000  0.0000
    3Eth     C2   10   1.329   0.198   0.252  0.0000  0.0000  0.0000
    3Eth     C3   11   1.203   0.286   0.252  0.0000  0.0000  0.0000
    3Eth     C4   12   1.076   0.201   0.252  0.0000  0.0000  0.0000
    4Eth     C1   13   1.958   0.286   0.252  0.0000  0.0000  0.0000
    4Eth     C2   14   1.833   0.198   0.252  0.0000  0.0000  0.0000
    4Eth     C3   15   1.707   0.286   0.252  0.0000  0.0000  0.0000
    4Eth     C4   16   1.580   0.201   0.252  0.0000  0.0000  0.0000
    5EthE    C1   17   2.463   0.286   0.252  0.0000  0.0000  0.0000
    5EthE    C2   18   2.338   0.198   0.252  0.0000  0.0000  0.0000
    5EthE    C3   19   2.212   0.286   0.252  0.0000  0.0000  0.0000
    5EthE    C4   20   2.085   0.201   0.252  0.0000  0.0000  0.0000
   2.52080   0.50416   0.50416

*with hdb file*
Eth     4
2       6       H1      C1      C2      -C4
2       6       H2      C2      C1      +C1
2       6       H3      C3      C2      +C1
2       6       H4      C4      C3      +C1
EthB    4
3       4       H1      C1      C2      +C1
2       6       H2      C2      C1      +C1
2       6       H3      C3      C2      +C1
2       6       H4      C4      C3      +C1
EthE    4
2       6       H1      C1      C2      -C4
2       6       H2      C2      C1      -C4
2       6       H3      C3      C2      -C4
3       4       H4      C4      C3      -C4

with rtp file:

; Polyethylene - this is an internal residue
[ Eth ]
 [ atoms ]
  C1    opls_136    -0.120    1
  H11   opls_140     0.060    1
  H12   opls_140     0.060    1
  C2    opls_136    -0.120    2
  H21   opls_140     0.060    2
  H22   opls_140     0.060    2
  C3    opls_136    -0.120    3
  H31   opls_140     0.060    3
  H32   opls_140     0.060    3
  C4    opls_136    -0.120    4
  H41   opls_140     0.060    4
  H42   opls_140     0.060    4

 [ bonds ]
  C1    -C4
  C1    H11
  C1    H12
  C1    C2
  C2    H21
  C2    H22
  C2    C3
  C3    H31
  C3    H32
  C3    C4
  C4    H41
  C4    H42
  C4    +C1
; Terminal PE residue ("beginning" of chain)
; designation arbitrary, C1 is -CH3
[ EthB ]
 [ atoms ]
  C1    opls_135    -0.180    1
  H11   opls_140     0.060    1
  H12   opls_140     0.060    1
  H13   opls_140     0.060    1
  C2    opls_136    -0.120    2
  H21   opls_140     0.060    2
  H22   opls_140     0.060    2
  C3    opls_136    -0.120    3
  H31   opls_140     0.060    3
  H32   opls_140     0.060    3
  C4    opls_136    -0.120    4
  H41   opls_140     0.060    4
  H42   opls_140     0.060    4

 [ bonds ]
  C1    H11
  C1    H12
  C1    H13
  C1    C2
  C2    H21
  C2    H22
  C2    C3
  C3    H31
  C3    H32
  C3    C4
  C4    H41
  C4    H42
  C4    +C1

; Terminal PE residue ("end" of chain)
; designation arbitrary, C2 is -CH3
[ EthE ]
 [ atoms ]
 C1    opls_136    -0.120    1
  H11   opls_140     0.060    1
  H12   opls_140     0.060    1
  C2    opls_136    -0.120    2
  H21   opls_140     0.060    2
  H22   opls_140     0.060    2
  C3    opls_136    -0.120    3
  H31   opls_140     0.060    3
  H32   opls_140     0.060    3
  C4    opls_136    -0.120    4
  H41   opls_140     0.060    4
  H42   opls_140     0.060    4
  H43   opls_140     0.060    4

 [ bonds ]
  C1    -C4
  C1    H11
  C1    H12
  C1    C2
  C2    H21
  C2    H22
  C2    C3
  C3    H31
  C3    H32
  C3    C4
  C4    H41
  C4    H42
  C4    H43

gro file generated by pdb2gmx: first few lines
62
    1EthB    C1    1   0.446   0.286   0.252
    1EthB   H11    2   0.419   0.382   0.252
    1EthB   H12    3   0.500   0.267   0.334
    1EthB   H13    4   0.500   0.267   0.170
    1EthB    C2    5   0.321   0.198   0.252
    1EthB   H21    6   0.265   0.185   0.170
    1EthB   H22    7   0.265   0.185   0.334
    1EthB    C3    8   0.195   0.286   0.252
    1EthB   H31    9   0.138   0.292   0.334
    1EthB   H32   10   0.138   0.292   0.170
    1EthB    C4   11   0.068   0.201   0.252
    1EthB   H41   12   0.011   0.191   0.170
    1EthB   H42   13   0.011   0.191   0.334
    2Eth     C1   14   0.950   0.286   0.252
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